Population Genetics Overview (Exam 3)

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Questions and Answers

What defines a population in biological terms?

Only those individuals that are able to migrate

Individuals of the same species that can interbreed in the same area (correct)

All organisms living in a given habitat

Individuals of different species in a particular area

Which mechanism of evolutionary change creates new alleles?

Natural selection

Genetic drift

Gene flow

Mutation (correct)

What type of mutations are inherited?

Benign mutations that do not affect fitness

Mutations affecting somatic cells

Any mutations in the organism's DNA

Mutations occurring in reproductive cells (correct)

How does gene flow affect populations?

It can reduce genetic differences between populations Signup and view all the answers

Which statement best describes genetic drift?

It results in a random change in allele frequencies Signup and view all the answers

What effect can deleterious mutations have on a population?

They may be eliminated through purifying selection Signup and view all the answers

Which scenario exemplifies gene flow in a beetle population?

Brown beetles migrate to a different population, increasing genetic variability Signup and view all the answers

In which population is genetic drift likely to have the most pronounced effect?

A small isolated population Signup and view all the answers

What phenomenon caused the increase in the black morph of the peppered moth by 1900?

Natural selection due to environmental changes Signup and view all the answers

How does antibiotic resistance in bacteria demonstrate natural selection?

Through variations caused by genetic mutations Signup and view all the answers

Why are carriers of sickle cell trait selected for in malaria-stricken regions?

They have a higher likelihood of survival against malaria Signup and view all the answers

What best describes coevolution?

Two species mutually influence each other's evolution Signup and view all the answers

What is an evolutionary arms race?

A process where species adapt in response to mutual threats Signup and view all the answers

How does sexual selection contribute to sexual dimorphism?

Through competition and choice based on specific traits Signup and view all the answers

What mechanism of microevolution involves a permanent change in DNA?

Mutation Signup and view all the answers

Which disease is mentioned as having individuals with genetic resistance within the population?

HIV Signup and view all the answers

What is the term for the event that leads to a sudden reduction in the alleles of a population?

Genetic bottleneck Signup and view all the answers

Which process leads to changes in allele frequencies that may occur when a new population is established?

Founder effect Signup and view all the answers

How does natural selection influence a population?

It allows certain heritable traits to produce more offspring. Signup and view all the answers

What refers to a trait that enhances an individual's fitness in a specific environment?

Adaptation Signup and view all the answers

What is meant by 'biological fitness' in the context of natural selection?

The ability to produce viable offspring relative to others. Signup and view all the answers

What defines genetic drift in a population?

Shift in allele frequencies due to random mating or death Signup and view all the answers

What is a key difference between natural selection and artificial selection?

Natural selection occurs in nature, while artificial selection involves human intervention. Signup and view all the answers

Which mechanism is considered random with respect to fitness?

Genetic drift Signup and view all the answers

What role do selective pressures play in a population?

They reduce survival and reproductive success of individuals. Signup and view all the answers

Which statement accurately describes natural selection?

It occurs when individuals with beneficial traits have more offspring. Signup and view all the answers

Why is genetic drift more pronounced in smaller populations?

Chance events can have a larger impact on allele frequencies. Signup and view all the answers

Which of the following is an example of microevolution?

Small-scale changes in allele frequencies within a population Signup and view all the answers

Which mechanism produces new alleles in a population?

Mutations Signup and view all the answers

Which of the following events would not be an example of natural selection?

A sudden reduction in alleles due to a genetic bottleneck Signup and view all the answers

What is a primary characteristic of macroevolution?

It results in the formation of new species. Signup and view all the answers

In what type of population is genetic drift likely to have a more pronounced effect?

Small populations with limited gene flow Signup and view all the answers

Which process involves organisms diversifying rapidly in response to new environmental challenges?

Adaptive radiation Signup and view all the answers

What is the main consequence of the Great American Biotic Interchange?

Migration of species from one continent to another Signup and view all the answers

Which of the following describes a characteristic that is a modified form of an ancestral trait?

Derived trait Signup and view all the answers

What defines sympatric speciation?

Speciation occurring without geographic separation Signup and view all the answers

What type of characteristic is used to illustrate evolutionary relationships in phylogenetic trees?

Derived traits Signup and view all the answers

Which evolutionary concept emphasizes that interactions with the environment drive evolution, instead of a goal-oriented process?

Evolutionary trends Signup and view all the answers

What type of changes occur due to evolutionary novelties?

Gradual modifications to existing structures Signup and view all the answers

In which scenario do species experience changes in biodiversity due to a breakdown of physical barriers?

Biotic interchange Signup and view all the answers

Which term describes organisms containing more than two paired sets of chromosomes?

Polyploidy Signup and view all the answers

In phylogenetic trees, what do synapomorphies represent?

Shared, derived characteristics among groups Signup and view all the answers

Study Notes

Population

A population refers to individuals of the same species inhabiting the same geographical area at a specific time, with the potential to interbreed.

Mutation

A permanent alteration in an organism's DNA sequence.
Mutations occur randomly and are the primary source of new alleles.
Only mutations affecting reproductive cells are passed down to offspring.
Mutations can be beneficial (positive) or detrimental (negative) to an organism's fitness.
Deleterious mutations are often removed by purifying selection, reducing their frequency.

Gene Flow

The movement of alleles between different populations.
Gene flow is a random process with respect to fitness.
Occurs through migration of individuals.
Can reduce genetic differences between populations.

Genetic Drift

A random fluctuation in allele frequencies within a population.
Often occurs due to random mating and death patterns.
It is a random process with respect to fitness.
Most prominent in smaller populations.
Can lead to the loss of alleles.

Natural Selection

Non-random process favoring individuals with heritable traits that increase survival and reproduction.
The only mechanism consistently contributing to adaptation within a population.
Influenced by selective pressures, such as environmental conditions (temperature, rainfall) and interactions with prey or predators.
Biological fitness refers to an individual's ability to produce viable offspring relative to others in the population.
Adaptation is a heritable trait enhancing an organism's fitness in a specific environment.
Artificial Selection is the intentional breeding of plants or animals for desired traits, often driven by human intervention.

Sexual Selection

A form of natural selection where individuals of one sex choose mates based on specific traits or behaviors.
Typically driven by female choice where males compete for mates.
Can lead to sexual dimorphism, where males and females of the same species display distinct physical characteristics.

Evolutionary Arms Race

A continuous cycle of adaptations between predator and prey species.
As one species evolves, the other responds with counter-adaptations, resulting in ongoing coevolution.

Coevolution

The reciprocal evolutionary influence between two species.
Occurs in predator-prey interactions, competitive species, and mutualistic relationships like pollinators and plants.

Microevolution

Small-scale evolutionary changes within a population resulting from allele frequency shifts.

Macroevolution

Large-scale evolutionary changes occurring over long periods (geologic time), leading to the formation of new species (speciation).

Speciation

The process of forming a new species through evolutionary mechanisms.

Adaptive Radiation

Rapid diversification of organisms, particularly when exposed to new environments with diverse challenges, resources, and ecological niches.
Often observed after mass extinction events or in isolated archipelagos (e.g., Galapagos finches).

Biotic Interchange

The breakdown of barriers between previously separated biotas, leading to significant biodiversity changes.
An example is the Great American Biotic Interchange, where the Isthmus of Panama connected North and South America, allowing the exchange of species.

Sympatric Speciation

The formation of new species without geographic separation.
Driven by ecological niche differentiation or polyploidy, resulting in reproductive isolation within a single population.

Evolutionary Novelties

Complex structures arise from gradual modifications to existing structures over evolutionary time.

Evolutionary Trends

Evolution is not goal-oriented.
The interaction between organisms and their environment drives evolution, not the desire for specific traits.

Taxonomy

The scientific classification of organisms based on hierarchical categories.

Phylogeny

The evolution of a group of organisms.

Phylogenetic Trees

Visual representations of evolutionary relationships among organisms.

Synapomorphy

A shared, derived characteristic used to support evolutionary relationships between taxa.

Ancestral Trait

A trait that existed in an ancestor

Derived Trait

A trait that is a modified form of an ancestral trait

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Description

This quiz covers essential concepts in population genetics, including definitions and implications of population, mutation, gene flow, and genetic drift. Explore how these factors influence the genetic makeup and evolution of species. Test your understanding of how allele frequencies change over time in populations.